With legalization of marijuana expanding and the risk of marijuana-associated impaired driving increasing, it is anticipated by the present inventors that there will be an increased need for portable and accurate measurement devices for quantifying levels of cannabinoid compounds, such as tetrahydrocannabinol (THC), that are present in a person's breath, e.g., such as during a traffic stop for suspected driving-under-the-influence. THC detection poses significant challenges since the amounts of THC that may be present in an exhaled breath are quite minute—much more so than is the case with alcohol. Furthermore, THC detection in human breath is generally the only reliable way to determine if a suspected marijuana user is under the influence. Unlike with alcohol, which the body can purge in relatively short order, e.g., less than a day, THC compounds may be present in a person's body long after they are no longer under the influence of the THC. Thus, detection of THC via blood or urine sample may result in false positives. Testing for THC in breath at the roadside would be convenient, non-invasive, and leverages the wide acceptance of administering a breath test at the roadside, as is commonly employed for alcohol.